orange pith, cheese and brown rice?

Friend who doesn't have asthma, tells me she's heard these foods contain something asthma sufferers lack. Never heard of it. Anyone else?

[Hidden]

Vitamin c, calcium and protein? Think we all lack that. I would think it depends on what kind of diet we have. I can't eat dairies but the dairy free products contain calcium these days.

Certain asthma meds can result a drop in potassium(i had that) and was told to eat bananas which I now do but haven't heard from anything else.

Anyone got any bright ideas? Would be interesting to know.

Love Lydia x